Document WO 00/46832 (FUJITSU) describes, in particular in FIG. 15, reproduced in FIGS. 1 and 2 below, a plasma panel, in which an array of barrier ribs define the cells 1 and includes a series of narrow ribs 2 that are continuous, parallel and directed along a first direction along with a series of thick ribs 3 that are discontinuous, parallel and directed along a second direction perpendicular to the first. The narrow ribs 2 define cell columns and the thick ribs 3 define cell rows. In each cell 1, each thick rib 3 is interrupted by a notch 4, 4′ that extends over the entire height of the rib. The notch is positioned in a plane of symmetry of the cell parallel to the direction of the columns.
For such a plasma panel, the side walls of the barrier ribs 2, 3 and the bottom of the cells 1 are generally covered with a layer of phosphor intended to emit visible light, generally red, green or blue, after excitation by radiation emitted by the plasma discharge in these cells.
In such a plasma panel, the arrangement of the pixels is generally organized in such a way that the adjacent cells of the same column, which are bounded by thick barrier ribs, are provided with phosphors of the same emission color. Adjacent cells of the same row, which are bounded by narrow barrier ribs, are provided with phosphors of different emission colors.
These phosphors are generally applied as a liquid paste, for example by screen printing or by dispensing. During application of this paste, the screen printing squeegee or the dispensing syringe is therefore moved in the direction of the columns in such a way that, between each cell, there is a risk of phosphors being unnecessarily deposited on the top of the thick ribs. Such deposition runs the risk of causing optical crosstalk phenomena between the cells and covering the notches 4, 4′. The notches 4, 4′ are important because they make it easier to pump the panel, that is to say to remove the gas between the plates before filling with the discharge gas, this being particularly useful when the barrier ribs are not porous.
However, such notches have drawbacks, especially that of also causing crosstalk, since the cells are less isolated from one another than when there are no notches. It is therefore recommended to limit the width of these notches, thereby reducing their effectiveness in preventing inopportune deposition of phosphors on the tops of the thick ribs.
One objective of the present invention proposes barrier rib structures that are better suited to preventing the risks of crosstalk.
Document EP 1 187 166 (FUJITSU) discloses a plasma panel having an array of cell-defining barrier ribs that is identical to the one just described, except that, instead of having notches passing through the thick ribs separating the rows of the cells, cavities are provided in the thickness of these ribs, which cavities emerge at the top of these ribs. Each cavity has side walls that isolate it from each of the adjacent cells and extend so as to be level with the tops of the ribs. Owing to the height of these walls, the risks of crosstalk are thus further reduced, since the adjacent cells are isolated from one another.
However, such an array of barrier ribs with cavities in their thickness has drawbacks such that during application of the phosphors, luminescent material may nevertheless be deposited on the tops of the barriers, outside the cavities. Also, there is a risk of encountering difficulties when pumping the panel, that is to say difficulties in removing the gas between the plates before filling with the discharge gas.
Document JP 56-134451 discloses a plasma panel having an array of barrier ribs that is quite similar to that disclosed in the aforementioned document EP 1 187 166. In that panel, the cavities separating the adjacent cells of the same column are used to initiate or ignite the discharges that then propagate in the cells. In no case are there notches connecting each cavity to the two adjacent cells of the same row.